Large aircraft components, such as a main landing gear drag brace, are subjected to high operating loads, including compression, tension, and bending. These parts must be sufficiently strong and durable to withstand these loads without detrimental permanent deformation and the corresponding ultimate loads without failure. At the same time, aircraft operators demand aircraft with components that are (1) more economically manufactured, and (2) lighter, both of which decrease the aircraft operating costs.
Components are often designed to include large pockets that reduce the amount of material in non-critical areas. Webs that form the bottoms of these pockets stabilize the structure surrounding the pockets, i.e., the pocket walls, by reacting compression loads and bending moments as shear through the webs. While additional weight saving can be realized by utilizing cutouts in the webs, these cutouts reduce the capability of the structure to withstand operational loads.
Currently, the use of web cutouts is limited by structural requirements. Although weight can be minimized with internal cut-outs, care must be taken to remain within margins of safety. The buckling allowable, P″, defines the maximum axial load a column can withstand prior to buckling. When bending moments and eccentricities are present, these further reduce the structural capability of the design due to the buckling combined with a beam behavior. For an axially loaded column, Euler's critical load formula can be used to approximate Pcr:
      P    cr    =                    π        2            ⁢      EI                      (        KL        )            2      
Where:
E is the modulus of elasticity for the column;
I is the second moment of area of the column's cross section;
L is the length of the unsupported section of the column; and
K is a factor which depends on the end conditions of the unsupported section (i.e. rotation/translation fixed/free).
Known solutions for increasing the buckling allowable of the part include (1) adding material to the beam column or change the geometry of its cross section to increase the second moment of area (increasing I) and/or (2) decreasing the length of the unsupported column section(s) (decreasing L). However, adding additional material increases the weight of the part significantly.